fix(ci): restore generated FlatBuffers files and drop debian:trixie from DEB test matrix

Restore metadata_generated.rs and metadata_hash_generated.rs as
tracked files — they are required by cargo fmt and the Rust module
system. Remove from .gitignore.

Drop debian:trixie from DEB test matrix. Ubuntu 24.04 ships libfuse3
with SONAME .so.3 while Debian trixie ships .so.4. A binary built on
Ubuntu cannot run on trixie due to the incompatible SONAME.

Author: imlk0

.github/workflows/build-deb.yml

@@ -85,8 +85,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        distro: ["ubuntu:24.04"]
         arch: [x86_64, aarch64]
-        distro: ["ubuntu:24.04", "debian:trixie"]
         include:
           - arch: x86_64
             runner: ubuntu-latest

cryptpilot-verity/src/metadata/.gitignore

@@ -1,2 +0,0 @@
-metadata_generated.rs
-metadata_hash_generated.rs